|10-21-2012 08:42 PM|
|Augusto||thanks a lot, I'm gonna put some miles on it and see how it performs|
|10-20-2012 10:10 PM|
|10-20-2012 07:15 PM|
|Augusto||do you think the shims may cause a geometry problem leading to wear/failure in the future?|
|10-20-2012 05:44 PM|
If I had to pick one thing it would be the difference in head gaskets.
If the difference in head gasket thickness were enough- and that could be a relatively small amount we're talking about here- that alone could account for the shims returning the lifter preload to a more normal position.
If the lifter retainer clips were missing, the shims wouldn't have fixed the problem so I think you can eliminate that as a possibility.
If different pushrods were used, that could have caused it, too. But it sounds like it went back together w/basically the same parts it started with.
|10-20-2012 04:07 PM|
Forgot to say before, the compression pressure rose from 60 to 130 psi
So the valves are sealing now for sure.
|10-20-2012 04:03 PM|
Hello my friends, this is an update.
I came to the conclusion that the valves were floating when the engine returned to idle, so I removed the rocker arms and it's pedestals and installed shims under them.
I added up to four 0.3mm shims and the engine run great, never missed a beat, but the valves made a bit of noise, so I removed one, for a total of 3 shims which is 0.9mm (0.035 in)
With this shims the engine runs quite well, not as smooth as with the 4 shims but the valves are quiet.
The problem is that this ford pedestals pair two valves so I can't adjust them individualy, I feel I should convert to a fully adjustable valvetrain.
What could be the cause of this? I doubt this engine had the head shaved, I talked to the previous owner who had it since new and he said he didn't touch the engine ever, I replaced the head gasket with a Victor unit, good brand name, I doubt they messed up, and I see the gasket has about the same thicknes as usual. Is ti possible for the lifters to break appart or loose the circlips or something else, that makes them stretch beyond their limits and keep my valves open?
BTW I installed a brand new Carb and electronic distribuitor, just to make sure this engine runs as economical and reliable as possible.
Please comment my friends.
|09-23-2012 11:14 PM|
|Augusto||thanks, I'll try to solve the rough idling issue then i'll fiddle with the timing as you suggest, I might even try the pertronix electronic conversion kit, I feel kinda too old school using points.|
|09-22-2012 08:56 PM|
I'd set it up to give as good of vacuum at idle as the initial timing will allow, then bring in the mechanical as quickly and as much as the engine/fuel/vehicle combo will allow w/o detonation. Basically same as any engine would be tuned, w/o having any predetermined numbers to work from.
But I just feel certain that you can work out a curve that will allow more initial- and that's the key to getting more vacuum and better throttle response off idle.
Be sure the vacuum chamber that's being used is advancing the ignition. You might try dialing in the timing w/o the vacuum advance at first, then bring it online after the curve is dialed in.
|09-21-2012 10:27 PM|
we don't have any emissions tests over here
|09-21-2012 10:20 PM|
the distrubuitor I'm using is a Motorcraft points type (late sixties maybe) with dual pot vaccum advance, I have only the end fitting of the vaccum pot connected to ported vaccum, the other, the one closer to the distruibuitor body is left open to the atmosphere. There's nothing in the vaccum line, like restrictors delayers or something, just a straight hose from the carb to the pot.
it's not a race engine, it's a daily driver but having it performing well is really cool.
|09-21-2012 10:18 PM|
now, since I live in a place where it's very hard to get parts for this engine, it really lures me the idea of converting the valvetrain to adjustable, I have a 250 I6 chevy engine that could donate the rockers, I understand that both chevy and ford use the same 1.6 ratio rockers, am I correct?
seems to me like installing some studs in place of the bolts will let me adjust the valvetrain, don't know if the head has push rod alignment guides.
|09-21-2012 10:09 PM|
I replaced the points and condenser by the way, didn't help
|09-21-2012 09:56 PM|
vacuum restrictor ?
The manufacturers used a lot of gadgets in the 70's to get the cars to pas US emmision standards , solenoids, to restrict vacuum, ,a plastic disc type thing looks kind of like a mini fuel filter that slowed down the change in vacuum, I had a Maverick 6 that would actually speed up when you first took your foot off the gas then slowly slow engine rpm,
|09-21-2012 07:37 PM|
|cobalt327||You should be able to use more than 8 degrees BTDC initial timing. It sounds like the mechanical advance may have too light springs or the vacuum advance is giving too much advance and or is deploying at too low of a vacuum signal.|
|09-21-2012 07:25 PM|
Having inadequate valve spring pressure can cause this. They could be allowing the lifters to pump up.
Be sure to check the lifter preload and geometry. Being that the valve train is non adjustable, the push rod length is critical.
Changes to the following will effect the p-rod length requirement:
Camshaft base circle diameter
Pushrod length due to wear or replacement
Different thickness head gaskets
Valve seat height changes from seat replacement or from valve seat grinding/cutting done during valve jobs
Grinding the tip of the valve stem when doing a valve job or different length valves
Lifter pushrod seat height due to different manufacturer
Change in rocker arm type or design, or ratio
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